Scanners typically allow the DPI resolution to be adjusted via software. For
best results, scanning should be done at the resolution of the intended
output device.

Example: You wish to scan an item of jewelry and print the item in your
catalog with the caption "Shown Actual Size."

If the catalog will be printed on a 600 DPI printer, the item should be scanned
with a resolution of 600 DPI, and care should be taken not to re-size or resample
the intermediate image file before printing.

When the output destination is a computer screen, as in the case of auction photos,
the scanned image may require further reduction using an image editor
before the image is physically small enough to fit on the viewer's screen.

Example: a book cover measuring 8 in. by 10 in. will produce an image height
of 750 Pixels even when scanned at only 75 DPI. Because many computer displays
are set at 800 X 600 Pixels, the resulting photo will be taller that the display
area and force scrolling.

Handy Tip! If you plan to create a new logo
or graphic using an image editor, Start by deciding the DPI setting which will
be used to print your design. You can then enter the desired size of the
graphic above and calculate the Pixel dimensions needed for the best print
quality. (Your original work can be resampled for an appropriate size web
image)

Monitor & Display Resolution

To determine the DPI resolution of your current display setting,
measure the width of the red line above with a household tape or ruler.
Consult the table at right to locate your measurement. The result will
be about four inches on most monitors. This is a common measurement
and explains why you will often see 75 DPI used when discussing
display resolution.NOTE! Be sure to check the zoom feature of your web
browser for this test. Set it to 100% or the measurements will be off
by the zoom (+/-) amount.

Measurement

Screen DPI

3 inches

100 DPI

3 &frac14 inches

92 DPI

3 &frac12 inches

85 DPI

3 &frac34 inches

80 DPI

4 inches

75 DPI

4 &frac14 inches

70 DPI

4 &frac12 inches

66 DPI

4 &frac34 inches

63 DPI

5 inches

60 DPI

What is a pixel? What is DPI? (Dots Per Inch)

You may think you don't know what a pixel is, but,
If you've ever seen a card stunt at a sports event, you probably do!
A pixel is simply the individual point of color on a digital image. A pixel doesn't
have a particular size. It is an abstract represention of a specific coordinate, like
a point on a map.
Just as individual sports fans hold up a colored card in the stadium, individual pixels
light up on your display to form a pattern. The only difference is the size of the point
when it is displayed.

This same concept extends to many other digital products. Pixel is used to describe the
number of descrete points that can be captured by digital cameras, and because most cameras
can actually recognize millions of points, the term Megapixel is used to shorten the
number of zeros needed.

Pixel indicates only a point on a grid, not the size of the point. Instead, Pixels
create a pattern based on the scale of the device being used. The photo shown here
is a good example. When the display device is the size of a stadium, the individual
pixels are the size of cards held by the people. When the display is the size of
the screen you are looking at, the pixels are so small that you may not be able
to see them individually.

For Printers and scanners, the individual points of color are often called
'dots' rather than pixels, but the concept remains the same as the stadium.
Because the output of a printer is paper which is usually measured in inches,
the term DPI or Dots Per Inch is used to communicate the scale or
physical size of each pixel.
Just as it takes many people seated in a grid to display a card stunt at the
stadium, a printer must place dots of color on paper to create a photo.

The scanner
performs this function in reverse, by recognizing the color at a specific row and
column
on the item being scanned. The scanner or digital camera actually records a file
of information indicating what color appeared at what position in the picture.
This is again the same principle as that of row and seat in the stadium.